Re: system drawings
kholland may be on to something:
"It seems too broad of a question. You have electrical systems, fire alarm systems, plumbing systems, roof systems, etc..."
Low-voltage systems like voice/data/video, cctv, catv, home theater, etc., often appear in a subset of electrical drawings sometimes labelled "special systems" or something like that. the idea is, i suppose, to distinguish this stuff from typical lighting, hvac, etc. plans, since they are often bid and installed by a different contractor.